Nerve Cells Talking to Silicon Chips

In the long term it will possibly enable the creation of very sophisticated neural prostheses to combat neurological disorders, and it could allow the creation of organic computers that use living neurons as their CPU. But in the much nearer term the new technology could enable very advanced drug screening systems for the pharmaceutical industry.

"The chip could be used to test the effect of drugs on neurons, to quickly discover promising avenues of research," says Professor Stefano Vassanelli, a molecular biologist with the University of Padua in Italy, and one of the partners in the NACHIP project, funded under the European Commission’s Future and Emerging Technologies initiative of the IST programme.

NACHIP's core achievement was to develop a working interface between the living tissue of individual neurons and the inorganic compounds of silicon chips. "We had a lot of problems to overcome," says Vassanelli. "And we attacked the problems using two major strategies, through the semiconductor technology and the biology."

NACHIP placed 16,384 transistors and hundreds of capacitors on a chip just 1mm squared in size. The group had to find appropriate materials and refine the topology of the chip to make the connection with neurons possible.

Biologically NACHIP uses special proteins found in the brain to essentially glue the neurons to the chip. "They also provided the link between ionic channels of the neurons and semiconductor material in a way that neural electrical signals could be passed to the silicon chip," says Vassanelli.

There, that signal can be recorded using the chip's transistors. And the neurons can also be stimulated through the capacitors. This is what enables the two-way communications. "Right now, we need to refine the way we stimulate the neurons, to avoid damaging them," says Vassanelli.